This invention relates to slide mounts and more particularly to such mounts which facilitate automatic loading of film transparencies into pre-closed slide mounts.
Film transparencies have long been clamped between masks to form photographic slides. In recent years, those transparencies have been automatically loaded through one edge of a slide mount formed of two joined masks. For example, in the U.S. Pat. No. 3,952,434 to Peter Florjancic, a transparency is pushed by a flat pusher element between spreadable transverse bridges of the two masks. These transverse bridges in the Florjancic mount normally have their inner faces in contact one with the other across the full width of the entranceway. Therefore, to provide sufficient room for inserting the film transparency these bridges must be bowed relatively widely apart, which is not a desirable operation; and this wide bowing of the bridge is accomplished by the exertion of a relatively large force, which is not desirable when pushing a relatively delicate film transparency into the pocket between the plastic masks. In other words, the Florjancic mount offers considerable resistance or impediment to the insertion of a film transparency, and the resultant significant forces involved can lead to operating problems or to damage of film transparency or mount. Because the pocket is spaced inwardly from the outer edge of the slide mount, it is necessary that the pusher follow the transparency through the entranceway, so that the film transparency becomes fully pushed into the pocket.
In U.S. Pat. No. 3,470,642 to Peter Mundt and Peter Florjancic is disclosed a slide mount having an insertion slot which extends fully across one end of the mount and also extends part of the way along the two side edges of the mount. Thus, the two border portions of the mount which define the insertion slot between them are entirely self-supporting for they each project parallel one to another in cantilevered relationship from the main body of the mount. These projecting, self-supporting border portions of the slide mount are likely to become snagged on neighboring objects. Also, the slot itself is unattractively large, extending completely across one end and partially along the two side edges; thus, the Mundt and Florjancic slot occupies all or part of three edges of the mount.
In my U.S. Pat. No. 4,102,029, which issued on July 25, 1978, there is disclosed an improved method and apparatus for loading transparencies into a preclosed slide mount. As set forth in that patent, a film transparency is cut from a film strip, and the cut transparency is pushed into the pre-closed slide mount by means of the film strip itself which is intentionally bent into a longitudinally bowed configuration in order to provide longitudinal strength, in the manner of a longitudinally bowed carpenter's measuring tape, while the entrance edge of the slide mount is spread by wedges during the insertion.
As explained in U.S. Pat. No. 4,102,029, there are a number of advantages of utilizing the bowed film strip as the pusher element. The film may be cut to form each individual transparency before, not after, the transparency is inserted into the slide mount. The moving parts are very light with low inertial forces, because the individual cut transparency has only a small amount of mass to be accelerated. By virtue of the fact that the end of the film strip is used as a pusher, the pusher cannot wear out, for a new cut end is exposed in each recurring cycle of operation. Thus, high rates of speed and efficient, fast slide-loading production can be obtained with low power consumption in a compact, reliable slide-loading machine.